The present invention relates generally to optical fiber arrays and micromachined chips used in optical fiber arrays. More specifically, it relates to a V-groove chip having a wick stop trench to prevent the uncontrolled wicking and movement of adhesive during manufacture of a V-groove fiber array.
Micromachined V-groove chips are commonly used in the optical fiber industry and photonics industry to align and position optical fibers. Typically, V-groove fiber arrays are made by placing optical fibers in V-grooves of a V-groove chip, placing a lid on the fibers, and then securing the assembly with adhesive. The lid can be a V-groove chip or a flat silicon or glass plate. The adhesive is typically a UV-curable or heat-curable epoxy.
The optical fibers must be carefully located in the V-grooves during manufacture of the array. Specifically, the optical fibers must be disposed in contact with the surfaces of the V-grooves. Also, for fiber arrays having polarization-maintaining fiber, the optical fibers must have an accurate rotational alignment. Also, some fiber arrays need to have optical fibers placed so that the fiber endfaces are fixed at different longitudinal positions.
It can be difficult to position optical fibers in conventional V-groove chips. This is because adhesive used to secure the fibers wicks by capillary action into the small spaces between the fibers and V-grooves. Since the adhesive wicks into these spaces, the entire length of the fiber is secured to the V-groove chip in a single step. It is not possible to secure the fiber in the V-groove in multiple gluing steps. This is a problem for certain fiber arrays because multiple gluing steps can improve the alignment of optical fibers.
U.S. Pat. No. 5,257,332 to Pimpinella discloses a fiber coupler having v-groove chips.
U.S. Pat. No. 5,748,822 to Miura et al. discloses a module for connecting an optical fiber to an optical element such as a laser diode. The module has a vertical groove cut perpendicular to the V-grooves. The vertical groove is positioned to abut the fiber endface and provide longitudinal positioning of the optical fiber.
Accordingly, it is a primary object of the present invention to provide a V-groove chip that:
1) controls wicking of adhesive so that optical fibers can be glued in multiple gluing steps;
2) provides for improved alignment of optical fibers in a V-groove chip;
3) provides for improved longitudinal alignment of optical fibers;
4) provides for improved rotational alignment optical fibers.
These and other objects and advantages will be apparent upon reading the following description and accompanying drawings.
These objects and advantages are attained by a V-groove chip having a wick stop trench. The wick stop trench intersects the V-groove. An optical fiber is disposed in the V-groove and crosses over the wick stop trench. The wick stop trench is filled with adhesive. The wick stop trench prevents adhesive from moving via capillary action along the entire length of the V-groove. This provides increased control over adhesive application and placement of the fiber in the V-groove. Preferably, the wick stop trench is deeper than the V-groove.
Preferably, the wick stop trench has vertical sidewalls. Also, the trench can be cut using a dicing saw.
The trench can have a width of about 20-500 microns or wider. More preferably the width is in the range of 100-200 microns. The wick stop trench can even be 1-5 mm wide if desired.
Preferably, the trench is perpendicular to the V-groove.
Also preferably, the trench divides the V-groove into groove sections of equal length. Preferably, the groove sections are at least 200 or 1000 microns long. Alternatively, the groove sections can be 10, 50, or 100 microns long.
The present invention includes a method for making a fiber array having a wick stop trench. In this method, an optical fiber is disposed in the V-groove. The fiber is glued to front and rear groove sections in separate gluing steps. Optionally, different adhesives are used in gluing the front and rear groove sections. Also, rotational or longitudinal alignment can be provided for the fiber before the fiber is glued to the front groove section. In a final step, the wick stop trench is filled with adhesive, and the adhesive is cured.